Identifying the terms and acronyms in classical conditioning can be like sorting through alphabet soup in another language! Don't let all those letters intimidate you, just remember that unconditioned is a cryptic way of saying unlearned. So whether it's the stimulus or the response, if it doesn't have to be taught or has an automatic/reflexive response, then it is unconditioned. Another way to think about this is to ask yourself, "would other people have a similar association without it being taught?" If so, then there's a good chance it's unconditioned.
Once pairing has successfully occurred, then everything changes over from unconditioned to conditioned.
